1. Field of the Invention
The present invention relates to a system for charging a battery provided in a legged walking robot by connecting an external power source to the legged walking robot.
2. Description of the Related Art
As a system for charging a battery provided in a robot, there has been known, for example, an industrial robot adapted to detect an absolute position of a movable part by an encoder, a backup battery being provided therein for uninterruptedly supplying current to the encoder so as to retain the data on the absolute position detected by the encoder even when the power line of the industrial robot is turned off (refer to, for example, Japanese Unexamined Patent Application Publication No. 5-228885).
There has been also known a mobile robot adapted to move among a plurality of work stations to carry out predetermined operations. While the mobile robot is halted at a work station, an external AC power source and the mobile robot are connected through the intermediary of the work station (refer to, for example, Japanese Unexamined Patent Application Publication No. 2000-326271). In this case, while the mobile robot is halted at a work station, a load of the mobile robot and a battery thereof are charged by the power supplied from the external AC power source, and power is fed from the battery to the load while the mobile robot is moving among work stations.
In the case of a legged walking robot using a battery as its power source, if the electric power supplied to joint motors of legs is cut off while charging the battery, then the action of each joint motor for retaining positions is lost, making it impossible to maintain a standing posture. Preferably, therefore, when charging the battery of the legged walking robot, the legged walking robot is connected to an external power source to supply charging current to the battery, and the current required to operate electric loads, such as joint motors, is also supplied from the external power source so as to enable the legged walking robot to continue its operation during the charging.